The optimal therapy for patients with relapsed or recurrent LCH has not been determined. Several regimens exist, including the following:
Patients with recurrent bone disease who recur months after stopping vinblastine and prednisone can benefit from treatment with a reinduction of vinblastine weekly and daily prednisone for 6 weeks. If there is no active disease or very little evidence of active disease, treatment can be changed to every 3 weeks, with the addition of oral mercaptopurine nightly.
An alternative treatment regimen employs vincristine, prednisone, and cytosine arabinoside. The prednisone dose is reduced from the dose used in the original publication.
Bisphosphonate therapy is also effective for treating recurrent LCH bone lesions. In a survey from Japan, bisphosphonate therapy successfully treated the bone lesions in 12 of 16 patients. Skin and soft tissue LCH lesions also resolved in the responding patients. None of the patients had risk-organ disease. Most patients received six cycles of pamidronate at 1 mg/kg/course, given at 4-week intervals. Eight of the 12 patients remained disease free at a median of 3.3 years. Other bisphosphonates, such as zoledronate and oral alendronate, have also been successful in treating bone LCH.[9,10]
Cladribine at 5 mg/m2 /day for 5 days per course has also been shown to be effective therapy for recurrent low-risk LCH (multifocal bone and low-risk multisystem LCH) with very little toxicity. Cladribine therapy should, if possible, be limited to a maximum of six cycles to avoid cumulative and potentially long-lasting cytopenias.
A phase II trial of thalidomide for patients with LCH (ten low-risk patients; six high-risk patients) who failed primary and at least one secondary regimen demonstrated complete (four of ten) and partial (three of ten) responses for the low-risk patients. Complete remission was defined as healing of bone lesions on plain radiographs (n = 3) or complete resolution of skin rash (n = 4, including 3 with bone lesions that had complete resolution). Partial response was defined as healing of bone lesion, but then worsening of a skin rash that was partially resolved. However, dose-limiting toxicities, such as neuropathy and neutropenia, may limit the overall usefulness of thalidomide. This agent is not used in pediatric patients to a significant degree.
Clofarabine is a proven effective therapy for patients with multiple relapses of low-risk or high-risk organs.